asterisk users - Apr 2005 - SMS with VOIP phone WIP 5000 from hitachi

All,

I added to my dialplan something like

exten => 777,1,SMS(0,s,530,Hello)

thinking this would send the "Hello" message to my SIP/530 phone 
(Hitachi WIP 5000).
The phone is working just fine just not receiving SMS yet. I enabled SMS 
on the phone.

I was just wanting to play with the SMS and just wanted to send the 
phone Hello
as a static message when I enter 777 from another phone.

What am I missing as this did not work. I read the wiki and thought I 
was doing
the correct thing.

Any suggestions is appreaciated.

Jerry